Frame transmission method and wireless communication apparatus performing the same

ABSTRACT

A frame transmission method and a wireless communication apparatus performing the same. A frame transmission method performed by a first wireless communication apparatus includes receiving subframe unit length information of a second wireless communication apparatus from the second wireless communication apparatus, determining a subframe unit length of the first wireless communication apparatus based on the received subframe unit length information, generating a plurality of subframes based on the determined subframe unit length, and transmitting a frame in which the generated subframes are aggregated to the second wireless communication apparatus, and wherein, when at least one of the subframes includes a padding, a length of the padding allows a length of the at least one of the subframes including the padding to be a multiple of a natural number of the determined subframe unit length.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the priority benefit of Korean PatentApplication No. 10-2015-0169204, filed Nov. 30, 2015, Korean PatentApplication No. 10-2015-0180974, filed Dec. 17, 2015, Korean PatentApplication No. 10-2016-0123322, filed Sep. 26, 2016, and Korean PatentApplication No. 10-2016-0154737, filed Nov. 21, 2016, in the KoreanIntellectual Property Office, the disclosure of which is incorporatedherein by reference for all purposes.

BACKGROUND

1. Field

One or more example embodiments relate to a frame transmission methodand a wireless communication apparatus performing the same.

2. Description of Related Art

For wireless close proximity communication, there exists high ratewireless personal area network (WPAN) technology that supports a hightransmission rate over a short distance. In a WPAN, a piconet mayinclude at least one device and one piconet coordinator (PNC). A deviceassociated with a parent piconet may become a PNC and thereby a childpiconet may be formed. In a mesh network including a parent piconet andchild piconets, a multi hop network is possible.

SUMMARY

According to an aspect, there is provided a frame transmission methodperformed by a first wireless communication apparatus, the methodincluding receiving subframe unit length information of a secondwireless communication apparatus from the second wireless communicationapparatus, determining a subframe unit length of the first wirelesscommunication apparatus based on the received subframe unit lengthinformation, generating a plurality of subframes based on the determinedsubframe unit length, and transmitting a frame in which the generatedsubframes are aggregated to the second wireless communication apparatus,wherein, when at least one of the subframes includes a padding, a lengthof the padding allows a length of the at least one of the subframesincluding the padding to be a multiple of a natural number of thedetermined subframe unit length.

The determined subframe unit length may be a greatest subframe unitlength among subframe unit lengths supported by both the first wirelesscommunication apparatus and the second wireless communication apparatus.

A last subframe among the subframes may not include the padding.

When the determined subframe unit length is N, the length of the paddingmay be one of 0 through N−1 and N is a natural number.

At least one of the subframes may include a payload and whether thepadding is included in the at least one of the subframes is determinedbased on a length of the payload.

The subframe unit length information of the second wirelesscommunication apparatus may be included in an association request frametransmitted by the second wireless communication apparatus.

The method may further include transmitting a beacon frame includingsubframe unit length information of the first wireless communicationapparatus to the second wireless communication apparatus.

According to another aspect, there is provided a first wirelesscommunication apparatus including a communicator configured to receivesubframe unit length information of a second wireless communicationapparatus from the second wireless communication apparatus, and aprocessor configured to determine a subframe unit length of the firstwireless communication apparatus based on the received subframe unitlength information and generate a plurality of subframes based on thedetermined subframe unit length, wherein, when at least one of thesubframes includes a padding, a length of the padding allows a length ofthe at least one of the subframes including the padding to be a multipleof a natural number of the determined subframe unit length.

The determined subframe unit length may be a greatest subframe unitlength among subframe unit lengths supported by both the first wirelesscommunication apparatus and the second wireless communication apparatus.

Additional aspects of example embodiments will be set forth in part inthe description which follows and, in part, will be apparent from thedescription, or may be learned by practice of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects, features, and advantages of the inventionwill become apparent and more readily appreciated from the followingdescription of example embodiments, taken in conjunction with theaccompanying drawings of which:

FIG. 1 is a flowchart illustrating a wireless communication methodaccording to an example embodiment;

FIG. 2 illustrates a frame transmission method performed betweenwireless communication apparatuses according to an example embodiment;

FIG. 3 is a block diagram illustrating a structure of a close proximitywireless communication system according to an example embodiment;

FIG. 4 is a diagram illustrating a structure of a media access control(MAC) frame body of an aggregated frame according to an exampleembodiment;

FIG. 5A is a diagram illustrating a data form stored in a media accesscontrol service data unit (MSDU) memory according to an exampleembodiment;

FIG. 5B is a diagram illustrating a data form stored in a frame memoryaccording to an example embodiment;

FIG. 6 is a diagram illustrating a structure of media access control(MAC) subframes according to an example embodiment; and

FIG. 7 is a block diagram illustrating a configuration of a firstwireless communication apparatus and a second wireless communicationapparatus for close proximity communication according to an exampleembodiment.

DETAILED DESCRIPTION

Hereinafter, some example embodiments will be described in detail withreference to the accompanying drawings. Regarding the reference numeralsassigned to the elements in the drawings, it should be noted that thesame elements will be designated by the same reference numerals,wherever possible, even though they are shown in different drawings.Also, in the description of embodiments, detailed description ofwell-known related structures or functions will be omitted when it isdeemed that such description will cause ambiguous interpretation of thepresent disclosure.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting. As used herein, thesingular forms “a,” “an,” and “the,” are intended to include the pluralforms as well, unless the context clearly indicates otherwise. It willbe further understood that the terms “comprises,” “comprising,”“includes,” and/or “including,” when used herein, specify the presenceof stated features, integers, steps, operations, elements, and/orcomponents, but do not preclude the presence or addition of one or moreother features, integers, steps, operations, elements, components,and/or groups thereof.

Terms such as first, second, A, B, (a), (b), and the like may be usedherein to describe components. Each of these terminologies is not usedto define an essence, order or sequence of a corresponding component butused merely to distinguish the corresponding component from othercomponent(s). For example, a first component may be referred to a secondcomponent, and similarly the second component may also be referred to asthe first component.

It will be understood that when an element is referred to as being“connected” or “coupled” to another element, it may be directlyconnected or coupled to the other element or intervening elements may bepresent. In contrast, when an element is referred to as being “directlyconnected” or “directly coupled” to another element, there are nointervening elements present. Other words used to describe therelationship between elements should be interpreted in a like fashion.

Unless otherwise defined, all terms, including technical and scientificterms, used herein have the same meaning as commonly understood by oneof ordinary skill in the art to which this disclosure pertains. Terms,such as those defined in commonly used dictionaries, are to beinterpreted as having a meaning that is consistent with their meaning inthe context of the relevant art, and are not to be interpreted in anidealized or overly formal sense unless expressly so defined herein.

Hereinafter, examples are described in detail with reference to theaccompanying drawings. Like reference numerals in the drawings denotelike elements, and a known function or configuration will be omittedherein.

FIG. 1 is a flowchart illustrating a wireless communication methodaccording to an example embodiment.

Referring to FIG. 1, the wireless communication method performed by awireless communication apparatus may generate a frame, for example, adata frame and a communication frame, in a close proximity wirelesscommunication system through below described processes and transmit thegenerated frame to another wireless communication apparatus. Forexample, the wireless communication apparatus may aggregate data of amedia access control (MAC) packet and generate a MAC frame.

In operation 110, the wireless communication apparatus generates a frameincluding a plurality of MAC subframes. For example, the wirelesscommunication apparatus may generate a MAC frame by aggregating aplurality of MAC subframes. Here, the wireless communication apparatusmay add a padding, hereinafter also referred to as a PAD, beingadditional data for adjusting a length (or a size) of a subframe to atleast one of subframes when needed. The padding may be provided, forexample, in a bit unit or a byte unit, and a value of a bit string ofthe padding may be variously defined.

For example, a length of a padding to be included in a subframe may bedetermined based on a length of a payload of the subframe. The wirelesscommunication apparatus may adjust the length of the subframe based on aunit for data processing and the length of the padding may be determinedbased on the corresponding unit for data processing. The wirelesscommunication apparatus may generate a frame by connecting a pluralityof subframes. A last subframe among the connected subframes may notinclude the padding according to an example embodiment. The wirelesscommunication apparatus may store the generated frame in a frame memory.

In operation 120, the wireless communication apparatus may transmit thegenerated frame to another wireless communication apparatus. A subheaderis included in the frame, and another wireless communication apparatusmay obtain information for dividing the frame from information includedin the subheader. Another wireless communication apparatus that receivesthe frame may separate the plurality of subframes from the frame basedon the information included in the subheader.

FIG. 2 illustrates a frame transmission method performed betweenwireless communication apparatuses according to an example embodiment.

Referring to FIG. 2, at least one of a first wireless communicationapparatus 210 and a second wireless communication apparatus 220 maygenerate a frame and transmit the frame to a counterpart apparatus.

The second wireless communication apparatus 220 transmits subframe unitlength information of the second wireless communication apparatus 220 tothe first wireless communication apparatus 210 in operation 230. Thesubframe unit length information of the second wireless communicationapparatus 220 refers to information on a length of a subframe, and theinformation is a reference used for generating each subframe. Thesubframe unit length information of the second wireless communicationapparatus 220 may be included in an association request frametransmitted by the second wireless communication apparatus 220.

The first wireless communication apparatus 210 receives the subframeunit length information of the second wireless communication apparatus220 from the second wireless communication apparatus 220, and determinesa subframe unit length of the first wireless communication apparatus 210based on the received subframe unit length information in operation 240.For example, the first wireless communication apparatus 210 maydetermine, as the subframe unit length of the first wirelesscommunication apparatus 210, a greatest subframe unit length amongsubframe unit lengths supported by both the first wireless communicationapparatus 210 and the second wireless communication apparatus 220.

The first wireless communication apparatus 210 generates the subframesbased on the determined subframe unit length in operation 250. The firstwireless communication apparatus 210 may adjust a length of a subframeby adding a padding to the subframe when a length of a subframe to begenerated is different from the determined subframe unit length. Alength of a padding included in a subframe allows a length of thesubframe including the padding to be a multiple of a natural number ofthe determined subframe unit length. The first wireless communicationapparatus 210 may exclude the padding from the last subframe when thesubframes are generated.

When the determined subframe unit length is N (natural number), thelength of the padding may be one of 0 through N−1. The length of thepadding being 0 indicates that the padding is not included in thesubframe. The subframe may include a payload and whether the padding isincluded in the subframe may be determined based on a length of thepayload. For example, when it is assumed that the determined subframeunit length is 4 bytes, a length of a header of the subframe is 4 bytes,and a length of a frame check sequence (FCS) is 4 bytes, (1) the lengthof the padding may be 0 bytes when the length of the payload of thecorresponding subframe is 8 bytes (that is, the padding is notincluded), (2) the length of the padding may be 3 bytes when the lengthof the payload of the corresponding subframe is 9 bytes, (3) the lengthof the padding may be 2 bytes when the length of the payload of thecorresponding subframe is 10 bytes, and (4) the length of the paddingmay be 1 byte when the length of the payload of the correspondingsubframe is 11 bytes. According to another example, the length of thepadding may be determined in bits.

The first wireless communication apparatus 210 generates a frame inwhich the subframes are aggregated and transmits the generated frame tothe second wireless communication apparatus 220 in operation 260.

The first wireless communication apparatus 210 may also transmitsubframe unit length information of the first wireless communicationapparatus to the second wireless communication apparatus 220. Here, thefirst wireless communication apparatus 210 may add the subframe unitlength information of the first wireless communication apparatus 210 toa beacon frame, and transmit the beacon frame to the second wirelesscommunication apparatus 220. The second wireless communication apparatus220 determines the subframe unit length based on the subframe unitlength information of the first wireless communication apparatus 210 inoperation 270. For example, the second wireless communication apparatus220 may also determine, as the subframe unit length of the secondwireless communication apparatus 220, the greatest subframe unit lengthamong the subframe unit lengths supported by both the first wirelesscommunication apparatus 210 and the second wireless communicationapparatus 220. The second wireless communication apparatus 220 generatesthe subframes based on the determined subframe unit length in operation280, and transmits the frame in which the subframes are aggregated tothe first wireless communication apparatus 210.

FIG. 3 is a block diagram illustrating a structure of a close proximitywireless communication system according to an example embodiment.

In an example, a wireless communication apparatus may store, in a mediaaccess control service data unit (MSDU) memory 320, data generated on anapplication layer 310 in a form of an MSDU. A MAC layer 330 may generatea MAC frame by reading the MSDU from the MSDU memory and store thegenerated MAC frame in a frame memory 340.

In an example, a physical (PHY) layer 350 of the wireless communicationapparatus may generate a PHY frame by reading the MAC frame from theframe memory 340, and the generated PHY frame may be wirelesslytransmitted through a radio frequency (RF) 360.

In an example, a process of receiving the PHY frame may be performed ina reverse order of a transmitting process described with reference toFIG. 3.

Referring to FIGS. 4 through 6, a MAC frame is described as an exampleof a frame. However, a scope of an example is not limited to a MACframe, and a technical description of the present disclosure may be alsoapplicable even when various frames are generated.

FIG. 4 is a diagram illustrating a structure of a media access control(MAC) frame body of an aggregated frame according to an exampleembodiment. In an example, a wireless communication apparatus may usethe aggregated frame to enhance an efficiency of data transmission. Astructure of the aggregated frame may differ based on a physical (PHY)layer to be used.

Referring to FIG. 4, a frame check sequence (FCS) and a padding areadded to a single MAC payload, and a subframe header is added based onan aggregation method to form a single MAC subframe. The padding may beadditional data used for adjusting a length of the MAC subframe. Thepadding may be used as dummy data for adjusting the length of the MACsubframe.

In an example, a MAC frame body of the aggregated frame may include atleast one MAC subframe. Here, a MAC subheader may be an optional header,and another wireless communication apparatus may receive the aggregatedframe and include information required for separating the receivedaggregated frame. The MAC subheader may be transmitted and received onthe PHY layer through a process that is the same as a process used totransmit a PHY header and a MAC header.

In an example, the MAC subframe included in the structure of theaggregated frame may include MSDU data being a payload, a 4-bytesubframe header, and a 4-byte FCS. Because a payload of the subframe hasa variable length, a 0 through 3-byte length of padding may be addedbased on the length of the payload. For example, when the length of thepayload is 5 bytes, the length of the padding may be 3 bytes. As anotherexample, when the length of the payload is 7 bytes, the length of thepadding may be 1 byte. Here, although the padding may be composed of0-bit and/or 1-bit units, a bit string configuration of the padding isnot limited thereto.

FIG. 5A is a diagram illustrating a data form stored in a media accesscontrol service data unit (MSDU) memory according to an exampleembodiment.

As a transmission rate of a close proximity wireless communication isincreased, data may be more frequently processed in 4-byte units in aclose proximity wireless communication system. However, a volume of anMSDU memory formed on an application layer may have a byte unit. In thiscase, as illustrated in FIG. 5A, MSDU data stored in the MSDU memory mayhave an empty space in an end portion of the MSDU memory, similar tofirst MSDU data and third MSDU data.

However, the frame memory including an aggregated frame may not requirean empty space. When a size of an end portion of the first MSDU data is3 bytes, a size of an end portion of a first subframe may be also 3bytes. Thus, 1-byte of data of each portion of a second subframe may beused to fill the empty space of the first subframe. In a receivingprocess, conversely, a process of using 1 byte of second MSDU datacorresponding to a second payload of the second subframe may berequired. In the close proximity wireless communication system, aprocess of using and filling a portion of data may be considerablyinconvenient and cause a decrease in performance.

The present disclosure may solve such issue through the proposedaggregated frame structure, such that the close proximity wirelesscommunication system may be easily implemented and performance of theclose proximity wireless communication system may be enhanced.

FIG. 5B is a diagram illustrating a data form stored in a frame memoryaccording to an example embodiment.

In an example, a wireless communication apparatus may store data in aframe memory as illustrated in FIG. 5B. A MAC subframe included in astructure of an aggregated frame may include MSDU data being a payloadof a subframe, a 4-byte subframe header, and a 4-byte FCS. Also, a 0through 3-byte length of padding may be added to a subframe based on alength of the payload. The padding may be additional data for adjustinga length of the subframe.

In an example, a length of the padding may be determined based on alength of the subframe or a length of the payload. For example, thewireless communication apparatus may determine the length of the paddingsuch that the length of the MAC subframe is a multiple of 4 bytescorresponding to a unit length of the subframe. Here, the padding mayinclude any type of data. For example, the padding may be filled with0-bit and/or 1-bit units.

Referring to FIG. 5B, the padding may be included in each of the firstsubframe and the third subframe such that the length of the subframe isa multiple of a subframe unit length. When the length of the subframe isa multiple of the subframe unit length, the padding may not be includedin the subframe as in the second subframe. For example, the wirelesscommunication apparatus may exclude the padding from a last subframe tobe included in the aggregated frame in order to enhance the transmissionefficiency.

FIG. 6 is a diagram illustrating a structure of a media access control(MAC) subframe according to an example embodiment.

Referring to FIG. 6, when a unit for data processing in a closeproximity wireless communication system is increased to be a 8-byte unitor a 16-byte unit other than a 4-byte unit, a wireless communicationapparatus may adjust a length of a padding included in a media accesscontrol (MAC) subframe to be 0 bytes through 7 bytes (when the length ofthe MAC subframe is 8 bytes) or 0 bytes through 15 bytes (when thelength of the MAC subframe is 17 bytes) such that the length of the MACsubframe is 8 bytes or 16 bytes.

In an example, the length of the padding may be determined based onbytes of the length of the MAC subframe. For example, when the length ofthe MAC subframe is 8 bytes, the length of the padding may be 0 bytesthrough 7 bytes in a structure of the MAC subframe. When the length ofthe MAC subframe is set to be N bytes, the length of the padding may be0 bytes through N−1 bytes.

Based on a method used for implementing a system, data may be processedin a 4-byte unit or a 8-byte unit. When units of data processed by twosystems are different, a system that processes data based on arelatively large unit for data processing may be used such thatcommunication may be possible. Thus, in the present disclosure, wirelesscommunication apparatuses may exchange respective pieces of subframeunit length information corresponding to information on a desired lengthof a MAC subframe before respective pieces of aggregated data areexchanged, such that the length of the MAC subframe to be exchanged bythe wireless communication apparatuses may be determined based on theexchanged pieces of information. The wireless communication apparatusmay compare the exchanged pieces of information and determine a subframeunit length of which a value is relatively great as a unit length to beapplied to subframes to be generated.

The aforementioned process performed by the wireless communicationapparatus may be performed in an association process of close proximitywireless communication. Subframe unit length information may be includedin a capability information element included in a beacon frame, and anassociation request frame or an association response frame.

In an example, a first wireless communication apparatus may receive thesubframe unit length information on the desired length of the MACsubframe from a second wireless communication apparatus. When thereceived subframe unit length information is greater than subframe unitlength information of the first wireless communication apparatus, thefirst wireless communication apparatus may determine the length of theMAC subframe based on the received subframe unit length information.Here, the subframe unit length information may be included in theassociation request frame transmitted by the second wirelesscommunication apparatus. In another example, the first wirelesscommunication apparatus may transmit first subframe unit lengthinformation on the length of the MAC subframe to the second wirelesscommunication apparatus, and receive second subframe unit lengthinformation on the length of the MAC subframe from the second wirelesscommunication apparatus. The first subframe unit length information maybe included in the beacon frame or the association response frametransmitted by the first wireless communication apparatus, and thesecond subframe unit length information may be included in theassociation request frame transmitted by the second wirelesscommunication apparatus. The length of the MAC subframe to be generatedby the first wireless communication apparatus may be determined based onsubframe unit length information that is greater between the firstsubframe unit length information and the second subframe unit lengthinformation.

FIG. 7 is a block diagram illustrating a configuration of a firstwireless communication apparatus and a second wireless communicationapparatus for close proximity communication according to an exampleembodiment.

Referring to FIG. 7, a first wireless communication apparatus 710 and asecond wireless communication apparatus 720 may correspond to the firstwireless communication apparatus 210 and the second wirelesscommunication apparatus 220 of FIG. 2, respectively.

The first wireless communication apparatus 710 includes a communicator714 and a processor 715. The communicator 714 transmits a beacon, aframe, a signal, data, information, or subframe unit length informationof the first wireless communication apparatus 710 to the second wirelesscommunication apparatus 720, or receives a beacon, a frame, a signal,data, information, or subframe unit length information of the secondwireless communication apparatus 720 from the second wirelesscommunication apparatus 720.

The processor 715 may perform at least one of operations described withreference to FIGS. 1 through 6. For example, the processor 715determines a subframe unit length of the first wireless communicationapparatus 710 based on the subframe unit length information of thesecond wireless communication apparatus 720 and generates a plurality ofsubframes based on the determined subframe unit length. The processor715 generates a frame by aggregating the generated subframes.

The second wireless communication apparatus 720 includes a communicator724 and a processor 725. The communicator 724 transmits the frame, thesignal, the data, the information, or the subframe unit lengthinformation of the second wireless communication apparatus 720 to thefirst wireless communication apparatus 710, or receives the frame, thesignal, the data, the information, or the subframe unit lengthinformation of the first wireless communication apparatus 710 from thefirst wireless communication apparatus 710.

The processor 725 may perform at least one of operations described withreference to FIGS. 1 through 6. For example, the processor 725determines the subframe unit length of the second wireless communicationapparatus 720 based on the subframe unit length information of the firstwireless communication apparatus 710, and generates the plurality ofsubframes based on the determined subframe unit length. The processorgenerates a frame by aggregating the generated subframes.

The components described in the exemplary embodiments of the presentinvention may be achieved by hardware components including at least oneDSP (Digital Signal Processor), a processor, a controller, an ASIC(Application Specific Integrated Circuit), a programmable logic elementsuch as an FPGA (Field Programmable Gate Array), other electronicdevices, and combinations thereof. At least some of the functions or theprocesses described in the exemplary embodiments of the presentinvention may be achieved by software, and the software may be recordedon a recording medium. The components, the functions, and the processesdescribed in the exemplary embodiments of the present invention may beachieved by a combination of hardware and software.

The apparatuses, units, modules, devices, and other components that aredescribed herein may be implemented using hardware components andsoftware components. For example, the hardware components may includemicrophones, amplifiers, band-pass filters, audio to digital convertors,non-transitory computer memory and processing devices. A processingdevice may be implemented using one or more general-purpose or specialpurpose computers, such as, for example, a processor, a controller andan arithmetic logic unit, a digital signal processor, a microcomputer, afield programmable array, a programmable logic unit, a microprocessor orany other device capable of responding to and executing instructions ina defined manner. The processing device may run an operating system (OS)and one or more software applications that run on the OS. The processingdevice also may access, store, manipulate, process, and create data inresponse to execution of the software. For purpose of simplicity, thedescription of a processing device is used as singular; however, oneskilled in the art will appreciated that a processing device may includemultiple processing elements and multiple types of processing elements.For example, a processing device may include multiple processors or aprocessor and a controller. In addition, different processingconfigurations are possible, such a parallel processors.

The software may include a computer program, a piece of code, aninstruction, or some combination thereof, to independently orcollectively instruct or configure the processing device to operate asdesired. Software and data may be embodied permanently or temporarily inany type of machine, component, physical or virtual equipment, computerstorage medium or device, or in a propagated signal wave capable ofproviding instructions or data to or being interpreted by the processingdevice. The software also may be distributed over network coupledcomputer systems so that the software is stored and executed in adistributed fashion. The software and data may be stored by one or morenon-transitory computer readable recording mediums.

The methods described according to the above-described exampleembodiments may be recorded in non-transitory computer-readable mediaincluding program instructions to implement various operations of theabove-described example embodiments. The media may also include, aloneor in combination with the program instructions, data files, datastructures, and the like. The program instructions recorded on the mediamay be those specially designed and constructed for the purposes ofexample embodiments, or they may be of the kind well-known and availableto those having skill in the computer software arts. Examples ofnon-transitory computer-readable media include magnetic media such ashard disks, floppy disks, and magnetic tape; optical media such asCD-ROM discs, DVDs, and/or Blue-ray discs; magneto-optical media such asoptical discs; and hardware devices that are specially configured tostore and perform program instructions, such as read-only memory (ROM),random access memory (RAM), flash memory (e.g., USB flash drives, memorycards, memory sticks, etc.), and the like. Examples of programinstructions include both machine code, such as produced by a compiler,and files containing higher level code that may be executed by thecomputer using an interpreter. The above-described devices may beconfigured to act as one or more software modules in order to performthe operations of the above-described example embodiments, or viceversa.

While this disclosure includes specific examples, it will be apparent toone of ordinary skill in the art that various changes in form anddetails may be made in these examples without departing from the spiritand scope of the claims and their equivalents. The examples describedherein are to be considered in a descriptive sense only, and not forpurposes of limitation. Descriptions of features or aspects in eachexample are to be considered as being applicable to similar features oraspects in other examples. Suitable results may be achieved if thedescribed techniques are performed in a different order, and/or ifcomponents in a described system, architecture, device, or circuit arecombined in a different manner and/or replaced or supplemented by othercomponents or their equivalents. Therefore, the scope of the disclosureis defined not by the detailed description, but by the claims and theirequivalents, and all variations within the scope of the claims and theirequivalents are to be construed as being included in the disclosure.

What is claimed is:
 1. A frame transmission method performed by a firstwireless communication apparatus, the method comprising: receivingsubframe unit length information of a second wireless communicationapparatus from the second wireless communication apparatus; determininga subframe unit length of the first wireless communication apparatusbased on the received subframe unit length information; generating aplurality of subframes based on the determined subframe unit length; andtransmitting a frame in which the generated subframes are aggregated tothe second wireless communication apparatus, wherein, when at least oneof the subframes includes a padding, a length of the padding allows alength of the at least one of the subframes including the padding to bea multiple of a natural number of the determined subframe unit length,and wherein the determined subframe unit length is a greatest subframeunit length among subframe unit lengths supported by both the firstwireless communication apparatus and the second wireless communicationapparatus.
 2. The method of claim 1, wherein a last subframe among thesubframes does not include the padding.
 3. The method of claim 1,wherein, when the determined subframe unit length is N, the length ofthe padding is one of 0 through N−1 and N is a natural number.
 4. Themethod of claim 1, wherein at least one of the subframes includes apayload and whether the padding is included in the at least one of thesubframes is determined based on a length of the payload.
 5. The methodof claim 1, wherein the subframe unit length information of the secondwireless communication apparatus is included in an association requestframe transmitted by the second wireless communication apparatus.
 6. Themethod of claim 1, further comprising: transmitting a beacon frameincluding subframe unit length information of the first wirelesscommunication apparatus to the second wireless communication apparatus.7. A first wireless communication apparatus, the apparatus comprising: acommunicator configured to receive subframe unit length information of asecond wireless communication apparatus from the second wirelesscommunication apparatus; and a processor configured to determine asubframe unit length of the first wireless communication apparatus basedon the received subframe unit length information and generate aplurality of subframes based on the determined subframe unit length,wherein, when at least one of the subframes includes a padding, a lengthof the padding allows a length of the at least one of the subframesincluding the padding to be a multiple of a natural number of thedetermined subframe unit length, and wherein the determined subframeunit length is a greatest subframe unit length among subframe unitlengths supported by both the first wireless communication apparatus andthe second wireless communication apparatus.
 8. The apparatus of claim7, wherein a last subframe among the subframes excludes the padding. 9.The apparatus of claim 7, wherein, when the determined subframe unitlength is N, the length of the padding is one of 0 through N−1 and N isa natural number.
 10. The apparatus of claim 7, wherein at least one ofthe subframes includes a payload and whether the padding is included inthe at least one of the subframes is determined based on a length of thepayload.
 11. The apparatus of claim 7, wherein the subframe unit lengthinformation of the second wireless communication apparatus is includedin an association request frame transmitted by the second wirelesscommunication apparatus.
 12. The apparatus of claim 7, wherein thecommunicator is configured to transmit a beacon frame including subframeunit length information of the first wireless communication apparatus tothe second wireless communication apparatus.